Uses for Special Characters in Java Code

Peter Lawrey

Aug. 14, 12 · Interview

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Ever wondered how you can write code like this in Java?

    if( ⁀ ‿ ⁀ == ⁀ ⁔ ⁀ || ¢ + ￠== ₡)

Background

Underscores has long been using in C like language such as Java to distinguish fields and method names.

It is common to see a leading underscore like _field or an underscore in a constant like UPPER_CASE. In Java the $ is also used in class names and accessor method names.

The SCJP has notes which state

Identifiers must start with a letter, a currency character ($), or a connecting character such as the underscore ( _ ). Identifiers cannot start with a number!

This leads to the question; what other connecting characters are there?

What are connecting characters?

A connecting character joins two words together. This page lists ten connecting characters

U+005F	LOW LINE	_	view
U+203F	UNDERTIE	‿	view
U+2040	CHARACTER TIE	⁀	view
U+2054	INVERTED UNDERTIE	⁔	view
U+FE33	PRESENTATION FORM FOR VERTICAL LOW LINE	︳	view
U+FE34	PRESENTATION FORM FOR VERTICAL WAVY LOW LINE	︴	view
U+FE4D	DASHED LOW LINE	﹍	view
U+FE4E	CENTRELINE LOW LINE	﹎	view
U+FE4F	WAVY LOW LINE	﹏	view
U+FF3F	FULLWIDTH LOW LINE	＿	view

And if you try the following you may find it compiles.

     int _, ‿, ⁀, ⁔, ︳, ︴, ﹍, ﹎, ﹏, ＿;

While this is interesting, does it have a use? Recently I found one.
I have an object which represents a column, and this column has a value for that row. The names are basically the same but I want a notation to distinguish them. So I have something like

    Column<Double>︴tp︴ = table.getColumn("tp", double.class);
    double tp = row.getDouble(︴tp︴);

This way I can see with is tp the column, and which is the value.

Interestingly the currency characters are valid as well.

 for (int i = Character.MIN_CODE_POINT; i <= Character.MAX_CODE_POINT; i++)
        if (Character.isJavaIdentifierStart(i) && !Character.isAlphabetic(i))
            System.out.println(i + " : " + (char) i);

prints

36 : $
95 : _
162 : ¢
163 : £
164 : ¤
165 : ¥
1547 : ؋
2546 : ৲
2547 : ৳
2555 : ৻
2801 : ૱
3065 : ௹
3647 : ฿
6107 : ៛
8255 : ‿
8256 : ⁀
8276 : ⁔
8352 : ₠
8353 : ₡
8354 : ₢
8355 : ₣
8356 : ₤
8357 : ₥
8358 : ₦
8359 : ₧
8360 : ₨
8361 : ₩
8362 : ₪
8363 : ₫
8364 : €
8365 : ₭
8366 : ₮
8367 : ₯
8368 : ₰
8369 : ₱
8370 : ₲
8371 : ₳
8372 : ₴
8373 : ₵
8374 : ₶
8375 : ₷
8376 : ₸
8377 : ₹
43064 : ꠸
65020 : ﷼
65075 : ︳
65076 : ︴
65101 : ﹍
65102 : ﹎
65103 : ﹏
65129 : ﹩
65284 : ＄
65343 : ＿
65504 : ￠
65505 : ￡
65509 : ￥
65510 : ￦

Java (programming language) Database

Published at DZone with permission of Peter Lawrey, DZone MVB. See the original article here.

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Uses for Special Characters in Java Code

Background

What are connecting characters?

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